Plastic articles and methods of making same



July 11, 1967 T. N. KOHLER ETAL 3,330,187

PLASTIC ARTICLES AND METHODS OF MAKING SAME 2 Sheets-Sheet 1 Filed Dec. 14, 1964 avg ONTACT POINT OF C v T N N Fu QM c m an N TEX /A/VEh/TOEi; THEODORE N. KOHLER Eow/mo F7. 5mm, 5y WE W,a@

HTTORNE K5 United States Patent Oflice 3,330,187 Patented July 11, 1967 3,33%),187 PLASTIC ARTICLES AND METHODS OF MAKING SAME Theodore N. Kohier, Uakiand, and Edward A. Send, St.

Louis, County, Mo., assignors to Western Textile Products Company, St. Louis, Mo., a corporation of Missouri Filed Dec. 14, 1964, Ser. No. 418,082 7 Claims. (Cl. 94-18) This invention relates to improvements in plastic articles and in methods of making same. More particularly, this invention relates to improvement in plastic joint formers and in methods of making same.

It is, therefore, an object of the present invention to provide an improved plastic joint former and an improved method of making same.

In constructing elongated masses of concrete, such as highways, canals, airport runways, retaining walls, and the like, it is customary to form joints in those masses of concrete. Those joints extend downwardly from the upper surfaces of those concrete masses, they extend transversely of those concrete masses, and they are intended to localize the cracking which usually occurs in those con crete masses. In some instances, those joints are formed by disposing joint formers in the concrete forms before the concrete is poured or cast. In other instances, those joints are formed by using rotary saws to cut elongated recesses in the upper surfaces of those concrete masses during the initial curing stages of those concrete masses. In still other instances, those joints are formed by forcing joint formers down into the concrete masses shortly after those concrete masses have been poured or cast. Once the joints have been formed, regardless of the manner in which they are formed, filling materials are introduced into those joints to fill and seal them.

Many different types and kinds of joint formers and joint-forming methods have been proposed, and several types and kinds of joint formers and joint-forming methods have been used; but none of those joint formers and joint-forming methods has been truly satisfactory. For example, joint formers which are disposed in the concrete forms before the concrete masses are poured or cast are not truly satisfactory because they keep the concrete masses from being poured or cast as monoliths of homogeneous nature. Further, those joint formers have to be heavy and bulky so they can withstand the forces to which they may be subjected as the concrete masses are poured or cast. Moreover, those joint formers must be carefully set and held within the concrete forms, to keep them from being displaced as the concrete masses are poured or cast. The method of forming joints by using rotary saws to cut elongated recesses in the initially cured concrete masses is not truly satisfactory, because the optimum time for the cutting is affected by temperature and humidity, and is thus not capable of precise determination. Frequently, the cutting of those elongated recesses must be done after normal working hours, and not infrequently at night. The cost of rotary saws of the diamond-tipped type is high, and rotary saws of the abrasive cutting wheel type require almost continuous adjustment to compensate for wear. Moreover, the elongated recesses formed by rotary saws are quite narrow; and the surfaces of those recesses are not clean and smooth. The joint formers that have been forced down into the concrete masses shortly after those masses have been cast or poured have not been truly satisfactory, because those joint formers have been hard to remove from the concrete masses. Further, some of those joint formers have been quite expensive. As a result, it would be desirable to provide a truly satisfactory joint former. The present invention provides a truly satisfactory joint former; and it does so by providing a joint former of plastic material which has a lower section that is readily embedded within and that will remain in the concrete, which has an upper section that is readily embedded in and that defines a recess in the concrete, and which has an intermediate section of reduced width that will permit the upper section to be pulled away from the lower section. The pulling away of the upper section from the lower section will clear the recess; and that recess can then be filled with a suitable filling and sealing material. The joint former provided by the present invention is relatively inexpensive, it is strong and rugged, it is easy to handle, and it can have the upper section thereof readily removed to define the recess for the filling and sealing material. It is, therefore, an object of the present invention to provide a joint former of plastic material which has a lower section that is readily embedded within and that will remain in the concrete, which has an upper section that is readily embedded in and that defines a recess in the concrete, and which has an intermediate section of reduced width that will permit the upper section to be pulled away from the lower section.

The lower section of the joint former provided by the present invention will underlie, and will constitute a seal for, the recess that is formed by the pulling of the upper section of that joint former away from that lower section. As a result, that lower section will coact with the filling and sealing material introduced into the recess, formed by the pulling away of the upper section, to keep water from lodging within the upper portion of the joint in the concrete mass. This is very desirable because it will protect the upper portion of the concrete mass against the cracking and crumbling which could occur if water was permitted to collect and then freeze in the upper portion of the joint. It is, therefore, an object of the present invention to provide a joint former which can be embedded in fresh concrete, and which has a lower section that will underlie and seal the recess which is formed by the pulling away of the upper section of that joint former.

The lower section of the joint former provided by the present invention has longitudinally-extending ribs thereon, and those ribs project laterally into the fresh concrete. Those ribs coact with the concrete to perform a dual function. First, those ribs solidly anchor that lower section in position within the concrete; and second, those ribs coact with the concrete to keep water from rising upwardly into the upper portion of the joint. As a result, the lower section of the joint former provided by the present invention will be held solidly within the concrete and well serve as a seal for the bottom of the recess that is formed when the upper section of that joint former is pulled away from that lower section. It is, therefore, an object of the present invention to provide a joint former with a lower section that has longitudinally-extending anchoring and sealing ribs thereon that project laterally into the concrete.

The upper section of the joint former provided by the present invention is generally frusto-triangular in configuration, and it has its widest dimension at the top thereof. Further, that upper section has die-smooth walls. As a result, that upper section will form a smooth-walled recess in the upper part of the concrete, and it can easily be removed from that recess. The upper section of the joint former provided by the present invention is homogeneous in nature, it is free of grain structure, it is resilient, and it is tough. As a result, that upper section can easily withstand the bending and tensioning forces that will be used to pull it away from the lower section and to pull it up out of the concrete. It is, therefore, an object of the present invention to provide a joint former with an upper section that is homogeneous in nature, is free of grain structure, is resilient, and is tough.

The joint former provided by the present invention is formed by an extruding process; and hence that joint former can be made die-smooth. Also, that joint former can be made economically and can be made with a high degree of uniformity and accuracy. The intermediate section of reduced width of the joint former provided by the present invention will be formed by permitting limited areas of the confronting faces of the upper and lower of the confronting faces of the upper and lower sections of that joint former'to engage and bond together asthose iipper and lower sections are extruded.

The extruding device that is used .to extrude the joint former of the present invention has a separating bar which is intended to permit just limited areas of the confronting faces of the upper and lower sections of that joint former to engage and bond together as those upper and lower sections are extruded; and that separating bar is disposedat the'exit face of the die plate. The disposition of that separating bar at that'exit face makes it possible to keep the width of the intermediate section of the joint former very uniform. It is, therefore, an object of the. present invention to provide a separating bar at the exit face of the die plate of an extruding device which is intended to extrude a joint former with an intermediate section of reduced width.

Other and further objects and advantages of the present invention should become apparentv from an examination of the drawing and accompanying description.

In' the drawing and accompanying description, some preferred embodiments of the present invention are shown and described but it is to be understood that the drawing and accompanying description are for the purpose of illustration only and do not limit the invention and that the invention will be defined by the appended claims.

In the drawing, FIG. 1 is a plan view, on a very small scale, of a length of concrete highway, i a FIG. 2 is a full scale, sectional view through the length ofconcrete highway shown in FIG. 1, and it is taken along the plane indicated by the line 22 in FIG.'1,

FIG. 3 is another full scale, sectional view through the length of concrete highway shown in FIG. 1, it is taken along the plane indicated by the line 33 in FIG. 1, and

. it shows'the recess that is formed when the upper section of the joint former is pulled away from the lower section of that joint former,

FIG. 4 is still another full scale, sectional view through the length of highway shown in FIG. 1, it is taken along the plane indicated by the line 44 in FIG. 1, and it shows a filling material disposed Within the recess of FIG. .3,

FIG. 5 is a still further full scale, sectional view through the length of concrete highway shown in FIG. 1, and it is taken along the plane indicated by the line 55 in FIG. 1,

FIG. 6 is a full scale end view of thejoint former provided by the present invention,

FIG. 7 is a diagrammatic view of the extruding device and of part of the cooling tank used in forming the joint former of FIG. 6,

FIG. 8 is a diagrammatic view of the rest of the cooling tank and of the belts which draw the extruded joint former away from the extruding device, 7

FIG. 9 is anendview of a joint former that is useful in forming joints in vertically-directed concrete structures,

FIG. 10 is a perspective view of the exit face of the die plate. of the extruding deviceof FIG. 7, and it shows the merging together of limited portions of the confronting faces of the upper and lower sections of the joint former ofFIG.6, f 7

' FIG. 11 is a full scale, 'elevational view'of the exit face of the die plate of the extruding device of FIG. 7,

FIG. 12 is a full scale, side view of the die plate, the

4 reservoir plates, the spreader plate, and the backing plate of the extruding device of FIG. 7,

FIG. 13 is a full scale, plan. view of the die plate, the reservoir plates, the spreader plate, and the backing plate of the extruding device of FIG. 7,

FIG..14 is an enlarged elevational view of the separating bar used in the extruding device of FIG. 7.

FIG. 15 is a side view, on the scale of FIG. 14, of the separating bar of FIG. 14, and

FIG. 16 is a sectional view through the separating bar of FIG. 14, and it is taken along the .plane indicated by the line 16-16 in FIG. 15.

Referring to the drawing in detail, the numeral 20 denotes the concrete which is used in forming part of a concrete slab; and that concrete can be poured or cast to any desired width'aud thickness. The concrete slab has -a number of transversely-extending joints in it; and one of those joints is generally denoted by the numeral 22, another of those joints is generally denoted by the numeral 24, and a third of those joints is generally denoted by the numeral 26. Those joints are formed'by the joint former of the present invention; and that joint former is shown in FIG. 6, and it is generally denoted by the numeral 28 The joint former 28 has a section 29, intermediate the top and bottom thereof, that defines a lower section 30 and an upper section 34. The lower section 30 is approximately triangular in cross section, and it has its smallest width portion at the bottom thereof. That lower section has a plurality of longitudinally-extending ribs 32 project-' ing outwardly from the side faces thereof; and those ribs are provided with fiat, horizontally-directed, upper faces and with outwardly and upwardly directed lower faces. Whilethe lower faces of the ribs 32 are shown as being arcuate, those lower faces could be plane. The upper section 34 of the joint former 28 is generally frustotriangular in cross section, and it has its largest width portion at the top thereof. The intermediate section 29 of the joint former 28 is much narrower than either, the upper section 34 or the lowersection 30. In one preferred form of the present invention, the top of the upper section 34 is onehalf of an inch wide, the intermediate section 29 is three thirty-seconds of an inchwide, and the top of the lowersection 30 is thirteen thirty-seconds of an inch wide. The upper section 34 is one-half of an inch high, the lower section 30 is one and one-half inches high, and the intermediate section 29 has virtually no height. The joint former 28 is made from a plastic material which is substantially unaffected by contact with concrete, which is substantially unaffected by exposure to the sun, which is substantially unaffected by exposure to water,

and which can withstand extremely low ambient temperatures as well as extremely high ambient temperatures. 7

Further, that joint former is formed from a plastic material which retains its resiliency indefinitely. Moreover, that joint former is made from a thermoplasticmaterial. While different materials could be used, polyvinylchloride' has been found to be very acceptable; because it is a resistant to rotting, it isresistant to wearing, and it does not'tend to crack or breakeven after long exposure to .sun, water, and extremely high or extremely low ambient temperatures.

The joint former 28 introduced into the concrete 2 0 very shortly after that concrete has been poured or cast;

and, usually, that joint former is introduced'into the concrete'after the completion of the last machine-screeda If desired, that joint former can be introduced into the concrete by mounting it within the jaws of a vibrating machine which will apply high frequency, low amplitude vibrations to that joint former while lowering that joint former down into the concrete. As the joint former 28 moves downwardly into the concrete, that concrete will yield to permit that joint former to move downwardly into it and will thereafter fully engage the bottom and sides of that joint former. The top of the upper section 34 will be closely adjacent the level of, and may form part of, the upper surf-ace of the concrete; but, during the hand finishing of the concrete, a thin layer of mortar may form and overlie the top of the upper section 24.

After the concrete has hardened, and upward force will be applied to one end of the upper section 34; and that upward force will pull the upper section 34 away from the lower section 39. As that upper section is pulled away, it will break away any layer of mortar which overlies the joint former, and it will also expose the recess at the top of the joint 24. Because the upper section 34 of the joint former 28 is made of plastic material and is die-smooth, that upper section will easily pull out of that recess. Also, because that upper section is made of plastic material and is die-smooth, the walls of the recess 25 will be smooth and will be free of cracks and crevices. If desired, the metal forms that are used in pouring or casting the concrete 20 can have notches formed therein adjacent the upper edges thereof to ac commodate outwardly-projecting extensions 35 that can be provided at the outer ends of the upper sections 34. Where such notches are formed in those forms, the joint formers 28 will be set in register with those notches, and the outwardly-projecting extensions 35 at the outer ends of the upper sections 34 of those joint formers will be laid in those notches. Then, after the forms have been removed, the outwardly-projecting extensions 35 can readily be grasped and raised upwardly to apply the forces which will pull the upper sections 34 away from the lower sections 30 of the joint formers 28.

If a contractor does not wish to notch the forms that are used in the pouring or casting of the concrete 20, but still wants to use the outwardly-projecting extensions 35, he can initially free the six to ten inches of the upper sections 34 which are spaced inwardly of those extensions before the joint formers are introduced into the concrete. The initially freed six to ten inches of the upper sections 34 will incline upwardly to and will overlie the tops of the forms that are used in the pouring or casting of the concrete 20, and will dispose the extensions 35 outwardly of those forms. Then, after the concrete has hardened and the forms have been removed, the outwardly-projecting extensions 35 can easily be gripped and raised upwardly to pull the upper sections 34 away from the lower sections 30. Such an arrangement is not quite as desirable as the arrangement wherein the forms are notched to accommodate the outwardly-projecting extensions 35; because the initially-freed portions of the upper sections 34 which rise up to and overlie the tops of the forms will, to some extent, impede the hand finishing of the concrete.

If a contractor does not wish to notch the forms that are used in the pouring or casting of the concrete 20, and if he does not wish to initially free short lengths of the upper sections 34 of the joint formers 28, he can use joint formers 23 that do not have outwardly-projecting extensions 35 thereon. The joint formers 28 will fit nicely between the forms, as those joint formers are introduced into the concrete; and hence those joint formers will not impede the hand finishing of that concrete. Then, after the forms have been removed, a separating tool which is chisel-like in configuration can be used to sever from six to ten inches of the intermediate sections 29 of the joint formers 28. That separating tool can then be used to raise the freed portions of the upper sections 34 upwardly through any thin mortar layer which overlies those upper sections; and, thereafter, those upper sections can be pulled away from the lower sections 30 of those joint formers.

The smooth-walled recesses 25 that are defined by the upper sections 34 of the joint formers 28 will be filled with a filling and sealing material 36 of standard and usual composition. That filling and sealing material will tend to adhere to the smooth-faced walls of the recesses 25 and to follow those smooth-faced Walls as the concrete 20 responds to changes in temperature to contract and expand. The filling and sealing material 36 will render the upper portions of the joints in the concrete substantially impervious to water, and it will thus keep water from working its way down into those upper portions and freezing. This is important; because if water were permitted to work its way down into the upper portions of those joints and freeze, the resulting ice could develop incipient or actual cracks in the upper portions of the concrete.

The positioning of the joint formers 28 within the upper portion of the concrete will make certain that if fissures or cracks develop in the concrete 20, those cracks or fissures will be overlain by the lower sections 30 of the joint formers 28. This is important; because in some areas water will tend to work its way up through cracks or fissures in the concrete. If that water were permitted to rise up to the level of the filling and sealing material 36, that water could freeze; and the resulting ice could develop incipient or actual cracks in the upper portions of the concrete. The lower sections 30 of the joint formers 28 will keep water from rising up to the level of the filling and sealing material 36 even if the concrete is in a wet area and even if cracks or fissures develop in that concrete below and in register with the joint formers 28. Specifically, the longitudinallyextending ribs 32 on the lower sections 30 of the joint formers 28 will project far enough into the concrete to coact with that concrete to constitute efiective barriers to any water which would tend to work its way up toward the filling and sealing material 36. As a result, the filling and sealing material 36 will coact with the lower sections of the joint formers 28 to keep the upper two inches of the expansion joints free from water. This is very important, because it makes certain that the upper two inches of each expansion joint will be substantially free of incipient and actual cracks.

In addition to serving as barriers to any water which tends to work its way up to the level of the filling and sealing material 36, the longitudinally-extending ribs 32 on the lower sections 33 of the joint formers 28 serve to solidly anchor those lower sections within the concrete. As a result, the lower sections 30 will be fixedly held by the concrete 20 as the upper sections 34 of the joint formers 28 are pulled away to form the recesses 25 in the upper portions of the joints. Consequently, the longitudinally-extending ribs 32 perform a dual function, namely, they perform the function of anchoring projections while also performing the function of barriers for any water which tends to work its way upwardly toward the level of the filling and sealing material 36.

The joint former 28 is formed as an extrusion, and it can be extruded in any lengths. Where that joint former is to be used in forming transverse joints for highways, it can be extruded in lengths of twelve or twenty-four feet. Where that joint former is to be used in forming transverse joints for airport runways, it can be extruded in lengths of twenty-five feet. However, where desired, that joint former can be extruded in lengths of several hundred feet and wound onto spools or reels. If a contractor wishes to bond two or more lengths of joint former 28 together to form a long joint former, he can easily do so. All that he needs to do is heat the confronting ends of the joint formers, press those heated ends together, and then permit them to cool.

The joint former 28 is very useful with concrete structures that are horizontally-directed or that are inclined FIG. 9 should be used. That joint former'is identical to the joint former 28 of FIG. 6, except that it has longitudinally-extending, laterally-projecting flanges 39 on the upper section 34 which lie in the plane of the upper face of that section. Those flanges can be three-eighths of an inch wide and one-eighth of an inch thick, and they will project outwardly from both sides of the upper section 34 to serve as nailing flanges.

In using the joint former 38, the upper section 34 and the flanges 39 will be set in abutting engagement with the interior of the form for the concrete structure; and nails will then be driven through those flanges and into that form to hold the joint former 38 in position. At such time,

' that joint former will extend inwardly at right angles 7 to the plane of the interior of that form; and, as that form is subsequently filled with concrete, the joint former3-8 will automatically form the desired joint in the concrete structure. After the concrete has hardened, the form will be removed; and the nails in the nailing flanges 39 will usually cause those flanges and the upper section 34 to pull away from the lower section 30, thereby opening the recess defined by that upper section. However, if those nails happen to pull throug those flanges, a workman can'grip those flanges and the upper section 34 and pull them away from the embedded lower section 30.

Referring particularly to FIGS. 7 and l13, the numeral 40 generally denotes an extruding device; and that extruding device has a chamber 41 in which plastic material is held in a heated condition and in which an extrusion screw is rotatably mounted. A backing plate 42 isrconnected to the outlet end of the chamber 41, areservoir plate 43 abuts'the front face of the backing plate 42, a spreader plate 45 abuts the front face of the reservoir plate 43, a second reservoir plate 47 abuts the front face of the spreader plate'45, and a die plate 49 abuts the front face of the second reservoir plate 47. Suitable bolts or screws, not shown, secure the chamber 41, the backing plate 42, the reservoir plate 43, the speaker plate 45, the second reservoir plate 47, and the die plate 49 together in liquid-tight relation. The chamber 41, the backing plate 42, the reservoir plate 43, the spreader plate 45, and the second reservoir plate 47 are not, perse, parts of the present invention; and they perform the functions which corresponding chambers, backing plates, spreader plates, and reservoir plates perform in the usual and customary extruding devices.

The die'plate 49 has a shallow slot 51 in the entering face thereof, and that slot extends from the top of that die plate to the bottom of that die plate. A large, generally-triangular passage is formed in die plate 49; and that passage extends from the entering face to the exit face of that die plate. The slot 51' intersects that passage; and a separator bar 53, which is disposed within slot 51, also intersects that passage. The separator bar 53 has. a separator pin 55 thereon; and that separator pin is disposed within, and extends from side to side of, the large, generally-triangular passage in the die plate 49. That separator pin coacts with that large, generally-triangular passage to define two separate orifices in the die plate 49.

- Specifically, that separator pin coacts with that large generally-triangular passage to define an orifice 48 for the lower section 30 of the joint former 28, and that separator pin' coacts with that large, generally-triangular passage to define an orifice 50 for the upper section 34 i of that joint former.

'The separator 'pin 55 has a leading edge that'is defined by two tapers of equal width; and that leading edge lies in the plane of the entering face of the die plate 49. That separator pin has a trailing 'edge that is defined by a taper 59 and a taper61, and part of that trailing edge" 'FIGS. 11 and 13-16. The tapered'leading and trailing edges on the separator pin 55 facilitate smooth and uniform movement of the plastic material past that separator pin. In the preferred form of the present inven 7 tion, the separator pin 55 completely. isolates the section of plastic material which issues through the orifice 50 from the section of plastic material which issues through the orifice 48. The isolated sections of plastic material are permitted to droop downwardly toward the water in a tank 52; and, at point 68 intermediate the exit face of the die plate 49 and the surface of that water, limited portions of the confronting faces of those sections of plastic material engage and unite with each other. Thereafter, the united sections droop down into the water in the tank 52; and they are supported, as they aremoved through that water, by supports 54. The water in the tank 52 is closely adjacent the point 68, as indicated by the Point of Entry Into Cooling Water shown by FIG. 10.

The water in the tank 52 will cool the united sections V sufficiently rapidly to keep the tensile strength of the material in the intermediate section 29 well below the tensile strengthof the material in the upper and lower sections 34 and 30, respectively;

The united sections will be gripped and held by cleats 62 on a belt 60 and by cleats 66 on a belt 64; The belt i 60 is mounted on, and rotated by, pulleys 56; and the lies in the plane of the exit face of that die plate. The

taper 59 is narrower than the taper 61, as shown by belt 64 is mounted on, and rotated by, pulleys 58. The

belts 60 and 64 are oriented so the cleats 62 on the belt 60 and the cleats 66 on the belt 64 are always in registry with each other as those belts are moved. The

belts 60 and 64, and the cleats 62 and 66 thereon, per- ;form a dual function. Specifically, those belts and those cleats draw the initially-isolated sections of plastic material away from the orifices 48 and 50 in the die plate 49 at such a rate that the confronting face-of the section V which issues from the orifice 50 and the confronting face 7 of the section which issues from the orifice 48 will be kept isolated until they have cooled slightly, but will be permitted to have portions thereof engageand unite with each other before they enter the water in the tank 52.. Subsequently, those belts and those cleats move the united sections to a cutting station where those united sections are cut into joint formers 28 of the desired length.

The rate of movement of the belts 60 and 64, andof the cleats 62 and 66 thereon, is regulated relative to the speed of the extrusion screw in the chamber 41 to determine the spacing between the point 68 and the exit face of the die plate 49. That spacing must be great enough to enable the confronting faces of the two initially-isolated sections of plastic material to cool sufficiently to keep all portions of those confronting faces from uniting with each other; and yet that spacing must I be small enough to keep the confrontingfaces of the two initiallyisolated sections of plastic material from cooling to such an extent that no portions of those confronting faces will unite with each other. Actually, that spacing must be-such that the confronting faces of the two initially isolated sections of plastic material will cool just enough to make operate at a linear speed of fourteen feet per minute and the extrusion screw rotates at a speed of sixty-six revolutions per minute. With those speeds, the intermediate section 29 was given a width ofthr'ee thirty-seconds of an inch; and that intermediate section entered the water in the tank 52 almost immediately after it Was formed. The resulting intermediate section is wide enough and strong enough to prevent. accidental separation of the upper section 34 from the lower section 30 but is narrow enough and weak enough 'to' enable moderate forces, which are well within the capabilities of any workman, to pull that upper section away from that lower section,

after that lower section has been embedded in concrete.

It is desirable for the reduced-width intermediate section 29 to be spaced inwardly from the side faces of the joint former 28, because such spacing protects that reduced-width intermediate section from injury during storage, shipment and handling at the job site. In the preferred embodiment of the present invention, the intermediate section 29 is closer to that face of the joint former 28 which issues from the lower portions of the orifices 48 and 50.

If desired, the separator bar 53 could be made so the separator pin thereon did not completely isolate the orifices 43 and 50 from each other and, instead, permitted thin webs to form adjacent the sides of those orifices. Those thin webs would continuously connect the outer edges of the confronting faces of the two sections extruded from those orifices. The belts 60 and 64, and the cleats 62 and 66 thereon, would then be moved at a speed which would keep the rest of the confronting faces of those sections from engaging and uniting with each other. A joint former that was made in that manner would have an intermediate section of reduced width which was constituted by two thin, spaced websone of those webs being adjacent to or forming part of the left-hand face of that joint former and the other of those webs being adjacent to or forming part of the right-hand face of that joint former. Those thin webs would enclose an empty area therebetween; and, while those webs would be thick enough to prevent accidental separation of the upper section 34 from the lower section 30 during storage, shipment, and handling at the job site, those webs would permit a workman to pull that upper section away from that lower section after that lower section was solidily embedded in concrete. Because the thin webs would overlie and conceal the hollow space between the confronting faces of the upper section 34 and the lower section 30, the extruding of a joint former with two webs would be more difficult than is the extruding of the joint former 28.

If desired, the intermediate section of reduced width could be formed by injecting a foreign substance between prescribed areas of the confronting faces of the sections which issue from the orifices 48 and 50. However, use of the separator bar 53 provided by the present invention obviates all need of injecting such a foreign substance between the confronting faces of those sections.

The space between the point of contact 68 and the exit face of the die plate 49 constitutes an atmospheric cooling zone; and the width of that zone will be a function of the melting temperature of the material being extruded, will be a function of the masses of the sections issuing from the orifices 48 and 50, will be a function of the spacing between those orifices, and will be a function of the relative speeds of the belts 60 and 64 and of the extrusion screw in chamber 41. In the preferred form of the present invention, the orifices 43 and 50 are separated by one hundred and forty-three thousandths of an inch and the width of the atmospheric cooling zone is three-quarters of an inch. However, where desired, the width of that atmospheric cooling zone can be varied; and, similarly, the size, composition, and configuration of the joint former 28 can be varied,

The fact that the intermediate section 29 has virtually no height is important, because it closely limits any tilting of the upper section 34 relative to the lower section 30. Specifically, because the intermediate section 29 has virtually no height, the confronting face of the upper section 34 will quickly engage and be held by the confronting face of the lower section 30. This means that the upper section will receive support from that lower section as well as from that intermediate section, whenever that upper section is tilted; and hence the joint former will be strongly resistant to injury due to tilting.

Whereas the drawing and accompanying description have shown and described some preferred embodiments of the present invention, it should be apparent to those skilled in the art that various changes may be made in the form of the invention without affecting the scope thereof.

What we claim is:

1. A one-piece joint former that comprises an elongated member of elastomeric, thermoplastic material which has:

(a) an upper section,

(b) a lower section,

(-c) an intermediate section of reduced width, and

(d) ribs on the sides of said lower section,

(c) said upper section having die-smooth walls,

(f) said upper section being frusto-triangular in configuration and having the widest dimension thereof at the top thereof,

(g) said lower section being generally triangular in configuration,

(h) said lower section having the narrowest dimension thereof adjacent the bottom thereof, so said joint former can easily be introduced into fresh concrete,

(i) said ribs extending longitudinally *of said lower section and projecting laterally outwardly from both sides of said lower section,

(j) said ribs being adapted to coact with the concrete, after said concrete has set, to fully anchor said lower section within said concrete,

(k) said ribs being adapted to coact with said concrete,

after said concrete has set, to keep water from entering the interfaces between said sides of said lower section and the concrete in engagement with said sides,

(1) said ribs having horizontally-directed upper faces,

(n1) said ribs having lower faces that incline outwardly and upwardly from said lower section,

(n) said intermediate section being short in height,

(0) said intermediate section being spaced inwardly from both of said sides of said lower section,

(p) the material of said intermediate section having a tensile strength less than the tensile strength of the material in said upper and lower sections,

(q) whereby said intermediate section will respond to upward forces applied to said upper section to tear, and thus permit said upper section to be separated from said lower section.

2. A one-piece joint former that comprises an elongated member of plastic material which has:

(a) an upper section,

(b) a lower section,

(c) an intermediate section of reduced width, and

(d) ribs on the sides of said lower section,

(e) said upper section having die-smooth walls,

(f) said upper section being frusto-triangular in configuration and having the widest dimension thereof at the top thereof,

(g) said lower section being generally triangular in configuration,

(h) said lower section having the narrowest dimension thereof adjacent the bottom thereof, so said joint former can easily be introduced into fresh concrete,

(i) said ribs extending longitudinally of said lower section and projecting laterally outwardly from both sides of said lower section,

(j) said ribs being adapted to coact with the concrete, after said concrete has set, to fully anchor said lower section within said concrete,

(k) said ribs being adapted to coact with said concrete,

after said concrete has set, to keep water from entering the interfaces between said sides of said lower section and the concrete in engagement with said sides,

(1) said intermediate section being short in height,

(m) said intermediate section being spaced inwardly from both of said sides of said lower section,

(n) the material of said intermediate section having a tensile strength less than the tensile strength of the material in said upper and lower sections,

() whereby said intermediate section will respond to upward forces applied to said upper section to tear, and thus permit said upper section to be separated from said lower section. V

3. A one-piece joint former that comprises an elongated'member of plastic material which has:

(a) an upper section,

(b) a lower section,

(0) an intermediate section of reduced width, and

(d) ribs on the sides of said lower section,

(e) said upper section having die-smooth walls,

7 (f) said upper section being frusto-triangular in configuration and having the widest dimension thereof at the top thereof,

(g) said lower section being generally triangular in configuration, 7 a

(h) said lower section having the narrowest dimension thereof adjacent the bottom thereof, so said joint a former can easily be introduced into fresh concrete,

(i) said ribs extending longitudinally of said lower section and projecting laterally outwardly from both sides of said lower section,

(i) said ribs being adapted to coact with the concrete after said concrete has set, to fully anchor said lower section Within said concrete,

(k) said ribs being adapted to coact with said concrete,

after said concrete has set, to keep water from enter- 1 ing the interfaces between said sides of said lower section and the concrete in engagement with said 7 sides, 7

(l) the material of said intermediate section having a tensile strength less than the tensile strength of the material in said upper and lower sections,

(In) whereby said intermediate section will respond to upward forces applied to said upper section to tear, and thus permit said upper section to be separated from said lower section.

" 4. A one-piece joint former that comprises an elongated member of plastic material which has:

(a) an upper section,

(b) a lower section,

(0) an intermediate section of reduced width, and

(d) ribs on the sides of said lower section,

(e) said upper section having die-smooth walls,

(if) said ribs extending longitudinally of said lower section and projecting laterally outwardly from both 'sides of said lower section,

(g) said joint former being adapted to be set in fresh concrete and said ribs being adapted to coact with the concrete, after said concrete has set, to fully anchor said lower section within said concrete,

(h) said ribs being adapted to coact with said concrete, after said concrete has set, to keep water from entering the interfaces between said sides of said lower section and the concrete in engagement with said sides,

(i) the material of said intermediate section having a tensile strength less than the tensile strength of the material intsaid upper and lower sections,

(j) whereby said intermediate section will respond to upward forces applied to said upper section to tear, and thus permit said upper section to be separated from said lower section;

5. A one-piece joint former that comprises an elongated member of.plastic material which has:

(a) 'an upper section,

(b) a. lower section, and t (c) an intermediate section ofreduced width,

'(d) the material'of said intermediate section having a tensile strength less than the tensile strength of the material in said upper and lower sections,

and a substantial portion of said upper section being adapted to be set in fresh concrete,

(j) said substantial portion of said upper section being adapted to be disposed within, and to have the opposite faces thereof in direct engagement with, said concrete,

(k) said intermediate section being adapted to betdisposed within, and to be located wholly below the exposed surface of, said concrete, 7 (1) said substantial portionof said upper section being adapted to move upwardly and away from the hardened concrete in engagement with said opposite faces thereof, and said lower section being adapted to remain within said concrete, as said intermediate section responds to upward forces applied to said upper section to tear, I (m) whereby said upper section is adapted to coact with said hardened concrete to form thesides of a recess and said lower section is adapted to underlie,

and form the bottom of, said recess. 7

6. A one-piece joint former that comprises an elongated member of plastic material which has:

an upper section, a a

a lower section,

an intermediate section that has a cross section which" is smaller than the cross section of either said upper section or said lower section, and

rib-like protuberancesron saidlower section,

said rib-like pr'otuberances extending longitudinally of said lower section and extending'outwardly from the opposite sides of said lower section,

said joint former being adapted to be dispose-d in fresh concrete,

said rib-like protuberances which extend outwardly from said opposite sides of said lower section being adapted to coact' with the concrete, after said concrete has set, to fully anchor said lower section witha in said concrete, said rib-like protuberances which extend outwardly from said opposite sides of saidlower section being adapted to coact with said concrete, after said concrete has set, to keep water from entering theinterfaces between said opposite sides of said lower section and the concrete in engagement with said opposite sides,

said intermediate section having a tensile strength that is less than the tensile strength of said upper section and that is less than the tensile strength of said lower section,

whereby said intermediate section will respond to upward forces applied to said upper section to tear, and thus permit said upper section to be separated from said lower section, a

said lower section responding to the anchoring action said upper section being adapted to be disposed within,

and to have the opposite faces thereof in direct engagement with, said fresh concrete,

said intermediate section being adapted to be disposed within, and to be located wholly below the exposed surfaces of, said fresh concrete,

said upper section being adapted to move upwardly and away from the hardened concrete in engagement with said opposite faces thereof, and to move upwardly and away from said lower section, as said intermediate section responds to upward forces applied to said upper section to tear,

whereby said upper section is adapted to coact with said hardened concrete to form the sides of a recess and said lower section is adapted to underlie, and form the bottom of, said recess,

said intermediate section having virtually no height,

whereby said upper section will separate from said lower section along a predetermined and fixed line immediately adjacent the top of said lower section, and

whereby the opposite sides of said joint former are generally continuous.

7. A one-piece joint former that comprises an elongated member of plastic material which has:

an upper section,

a lower section,

said lower section having the bottom thereof narrower than the top thereof to facilitate the insertion of said joint former into fresh concrete,

an intermediate section that has a cross section which is smaller than the cross section of either said upper section or said lower section, and

ribs on the sides of said lower section,

said ribs extending longitudinally of said lower section and projecting laterally outwardly from both sides of said lower section,

said joint former being adapted to be disposed in fresh concrete with said narrow bottom of said lower section serving to facilitate the insertion of said joint former into said fresh concrete and said wider top of said lower section serving as a wedge to spread the confronting portions of said fresh concrete far enough apart to enable said upper section of said joint former to move into position between the upper areas of said confronting portions,

said ribs which extend longitudinally of said lower section and which project laterally outwardly from both sides of said lower section being adapted to coact with the concrete, after said concrete has set, to fully anchor said lower section within said concrete,

said ribs which extend longitudinally of said lower section and which project laterally outwardly from both sides of said lower section being adapted to coact with said concrete, after said concrete has set, to keep water from entering the interfaces between said sides of said lower section and the concrete in engagement with said sides,

said intermediate section having a tensile strength that is less than the tensile strength of said upper section and that is less than the tensile strength of said lower section,

whereby said intermediate section will respond to upward forces applied to said upper section to tear, and thus permit said upper section to be separated from said lower section,

said lower section responding to the anchoring action of said ribs, which extend longitudinally of said lower section and which project laterally outwardly from both sides of said lower section, to remain within said concrete as said intermediate section is torn to permit said upper section to move upwardly and away from said lower section,

said upper section being adapted to be disposed within,

and to have the opposite faces thereof in direct engagement with, said fresh concrete,

said intermediate section being adapted to be disposed within, and to be located wholly below the exposed surfaces of, said fresh concrete,

said upper section being adapted to move upwardly and away from the hardened concrete in engagement within said opposite faces thereof, and to move upwardly and away from said lower section, as said intermediate section responds to upward forces applied to said upper section to tear,

whereby said upper section is adapted to coact with said hardened concrete to form the sides of a recess and said lower section is adapted to underlie, and form the bottom of, said recess.

References Cited UNITED STATES PATENTS 789,992 5/ 1905 Miller. 1,982,580 11/1934 Fischer 9418.2 2,230,303 2/1941 Leguillon 9418.2 3,052,945 9/1962 Cummings 9451 XR 3,136,022 6/1964 Dohren 9451 XR 3,180,238 4/1965 Crone 94-13 3,234,860 2/1966 Lacy 94-48 JACOB L. NACKENOFF, Primary Examiner. 

1. A ONE-PIECE JOINT FORMER THAT COMPRISES AN ELONGATED MEMBER OF ELASTOMERIC, THERMOPLASTIC MATERIAL WHICH HAS: (A) AN UPPER SECTION, (B) A LOWER SECTION, (C) AN INTERMEDIATE SECTION OF REDUCED WIDTH, AND (D) RIBS ON THE SIDES OF SAID LOWER SECTION, (E) SAID UPPER SECTION HAVING DIE-SMOOTH WALLS, (F) SAID UPPER SECTION BEING FRUSTO-TRIANGULAR IN CONFIGURATION AND HAVING THE WIDEST DIMENSION THEREOF AT THE TOP THEREOF, (G) SAID LOWER SECTION BEING GENERALLY TRIANGULAR IN CONFIGURATION, (H) SAID LOWER SECTION HAVING THE NARROWEST DIMENSION THEREOF ADJACENT THE BOTTOM THEREOF, SO SAID JOINT FORMER CAN EASILY BE INTRODUCED INTO FRESH CONCRETE, (I) SAID RIBS EXTENDING LONGITUDINALLY OF SAID LOWER SECTION AND PROJECTING LATERALLY OUTWARDLY FROM BOTH SIDES OF SAID LOWER SECTION, (J) SAID RIBS BEING ADAPTED TO COACT WITH THE CONCRETE, AFTER SAID CONCRETE HAS SET, TO FULLY ANCHOR SAID LOWER SECTION WITHIN SAID CONCRETE, (K) SAID RIBS BEING ADAPTED TO COACT WITH SAID CONCRETE, AFTER SAID CONCRETE HAS SET, TO KEEP WATER FROM ENTERING THE INTERFACES BETWEEN SAID SIDES OF SAID LOWER SECTION AND THE CONCRETE IN ENGAGEMENT WITH SAID SIDES, (L) SAID RIBS HAVING HORIZONTALLY-DIRECTED UPPER FACES, (M) SAID RIBS HAVING LOWER FACES THAT INCLINE OUTWARDLY AND UPWARDLY FROM SAID LOWER SECTION, (N) SAID INTERMEDIATE SECTION BEING SHORT IN HEIGHT, (O) SAID INTERMEDIATE SECTION BEING SPACED INWARDLY FROM BOTH OF SAID SIDES OF SAID LOWER SECTION, (P) THE MATERIAL OF SAID INTERMEDIATE SECTION HAVING A TENSILE STRENGTH LESS THAN THE TENSILE STRENGTH OF THE MATERIAL IN SAID UPPER AND LOWER SECTIONS, (Q) WHEREBY SAID INTERMEDIATE SECTION WILL RESPOND TO UPWARD FORCES APPLIED TO SAID UPPER SECTION TO TEAR, AND THUS PERMIT SAID UPPER SECTION TO BE SEPARATED FROM SAID LOWER SECTION. 